This invention relates to solar collectors which utilize air or other gaseous heat exchange media.
The basic principle of solar collectors is quite old, such collectors usually including a box-like enclosure with a transparent cover which forms a chamber. An absorber panel with conduits for water, air or other heat exchange media is located in the chamber, spaced from the cover. The interior of the chamber and the conduits are provided with a black coating to increase their absorptivity to solar radiation. Radiant energy is absorbed to heat the interior of the chamber, and the heat is removed by a heat exchange medium circulated through the conduits.
There has been extensive activity in recent years in attempting to improve the efficiency of solar collectors. This invention represents yet another approach to such efficiency improvement.
Prior solar collectors have often had an absorber panel located in the chamber, spaced from both the cover and the bottom of the chamber. Gaseous heat exchange media have been flowed either through the upper or lower space. According to one aspect of the present invention, the spaces both above and below the absorber conduits are provided with inlets and outlets which enable a heat exchange medium to flow therethrough. The heat exchange medium flowing through the upper space removes heat from the chamber and reduces heat losses through the cover, while the heat exchange medium flowing through the lower space removes heat from the chamber and reduces heat transmission to the bottom of the enclosure. Preferably, the primary conduits are provided by a pair of adjacent sheets having mutually contacting longitudinally extending areas and mutually spaced longitudinally extending areas. This structure is supported on a corrugated member located in the lower space and provided with peaks which underlie and support the primary conduits. An apertured baffle distributes the incoming heat exchange medium to the various conduits and spaces, the baffle providing inlets to the upper and lower spaces which is less than the total area of the inlets leading to the primary conduits.
According to another aspect of the invention, heat losses through the side walls of a collector enclosure are reduced by providing a side conduit which extends along the side of the collector chamber. The side conduit is provided with inlet and outlet means for enabling a heat exchange medium to flow therethrough to reduce heat losses through the walls. Preferably, the outlet means for the side conduit leads to the space in the collector chamber which lies between the cover and the absorber conduits.
For a further understanding of the invention, reference is made to the following description and drawings of a preferred and exemplary embodiment.